SEXUAL AND ASEXUAL REPRODUCTION 251 



very short or they may be long and coiled. Sperms are much 

 smaller than eggs, the sperm being always microscopic. Plants 

 also produce sperms (Fig. 120 G), though they do not come 

 from spermaries or special sperm ducts; see page 271. 



Males, Females, and Hermaphrodites. When reproduction 

 in animals or plants is brought about by eggs and sperms, 

 the process is spoken of as sexual reproduction and the uniting 

 bodies, the eggs and sperms, are sex bodies. The glands that 

 produce them are the sexual glands, or gonads, and the ducts 

 that conduct the bodies to the exterior are the sexual ducts. 

 Among animals, it is most common to have one individual 

 produce either spermaries or ovaries, but not both, and the 

 individuals are then spoken of as males and females.* 



In some animals, however, as already seen in the earthworm, 

 the same individuals may produce both spermaries and ovaries. 

 Such individuals are spoken of as hermaphrodites. Among 

 animals hermaphrodites are found chiefly among the lower 

 orders, very few being found among the higher. Among plants, 

 however, both hermaphroditic and separate sexed conditions 

 are common; hermaphroditic plants are called monoecious 

 (Gr. monos = one + oikos = house), and the separate sexed 

 plants dioecious (Gr. di- = twice -f- oikos). In the higher 

 flowering plants the relation of the sexes is peculiar, and com- 

 plicated by what is called alternation of generations, to be 

 described later. 



THE UNION OF THE SEX BODIES OR FERTILIZATION 



The union of the egg and the sperm is called fertilization, 

 and the moment when the egg and the sperm unite is the 

 beginning of the life of the new individual. This process of 

 union of the sex bodies is peculiar and of extreme significance. 

 In the description which follows, the successive changes which 

 occur are described without reference to any particular spe- 



*The sign $ is used to denote the male sex, 9 to denote the female sex, 

 and $ to denote hermaphrodites. 



